As US President Donald Trump provokes trade tensions with major partners, Belgian chemicals group Solvay is questioning whether its investments in the United States make sense, CEO Jean-Pierre Clamadieu said on Sunday.

Clamadieu said Solvay had set up factories in countries such as China and the United States assuming that they could easily ship to other markets.

“The fact that all of a sudden barriers are popping up leads us to ask questions, such as, can we keep investing in the United States?” Clamadieu said.

“If we see that a trade war is setting in for the long haul, it will put into question our strategies for locating” operations, he said, speaking on the sidelines of an economics conference in Aix-en-Provence in southern France attended by many French CEOs.

Trump’s administration, which has already imposed tariffs on steel and aluminium made in the EU, Canada and Mexico, has threatened a tariff increase on all EU-assembled vehicles.

French Finance Minister Bruno Le Maire insisted on Sunday that Europe would retaliate against further hikes, although Germany has signalled that it is prepared to accept lower EU import car tariffs to ease tensions with Washington, something Paris is unlikely to accept.

Clamadieu, a Frenchman, said it was clear that there were risks of cracks appearing in Europe’s united response to the US.

“Europe has institutional tools, but what it is missing is strong leaders capable of hitting a fist on the table with as much strength as needed,” he said.